Hanna Instruments PCA 310 - Manual (Page 25)

25
Acid/alkali Dosing Relay
Acid/alk dosing relay is activated (Common connected
to Normal Open) depending on the setpoint and
selected delta. If the analyzer is set to dose acid, the
relay is active when the pH value is over the setpoint.
If alkaline is dosed, the relay is activated when the
pH value is under the setpoint.
The DOSING ACID/ALK. LED is turned on when the dosing
relay is closed.
Note: The acid/alk dosing is stopped when system error related to
pH occurs.
Recorder Outputs
The recommended recorder hookup uses a twisted
pair shielded cable. The shield should be connected
to the terminal at the instrument end and left open
at the recorder end.
To operate with this hookup, the following conditions
are required at the recorder end:
• The input to the recorder must be isolated from the chassis
ground (earth) of the recorder;
• If the recorder has more than one input, they must be
differential inputs.
Two types of outputs are available: 0-20 mA or 4-20 mA for
each output. The recorder outputs could be assigned to Cl,
pH, Temperature or ORP.
Proportional dosing pump
Two proportional dosing pumps could be connected to the 4-20
mA outputs. The pump could be used to dose chlorine and
acid/alk as selected by the user. When the output is 4 mA, the
pump must be stopped and when the output is 20 mA, the
pump must provide the maximum output.
RS485
The analyzer has RS485 serial communication
with selectable baud rate between 1200 and
9600 Bps. The GSM module HI 504900 is also
connected using the RS485 port.
Note: The RS485 could use also the ground wire to
prevent common mode voltages.
DOSING
pH
DOSING
pH
C NO
RS 485 RS 485
B A I I